Third Quarter Review Sheet Answers

Third Quarter Review Sheet Answers REACTIONS: 1. Define and explain how precipitates are formed? Identify the type of reaction for 2-6 2. C3H5(NO3)3 heat  → CO2 + N2 + H2O + O2 3. Zn + 2HCl → ZnCl2 + H2 single replacement 4. Pb(NO3)3 + K2CrO4 → PbCrO4 + KNO3 5. 2C6H6 + 15O2 → 12CO2 + 6H2O 6. 3H2 + N2 → 2NH3 decomposition double replacement combustion synthesis Balance the equations for questions 7 through 11 7. 2HgO + Cl2 → 2HgCl + O2 8. C2H4 + 3O2 → 2CO2 + 2H2O combustion 9. Ca(OH)2 + 2HNO3 → Ca(NO3)2 +2 H2O 10. P4 + 5O2 → P4O10 11. 4FeS2 + 11O2 → 2Fe2O3 + 8SO2 by 2 2FeS2 + 5.5 O2 → Fe2O3 + 4SO2 can’t have half multiply 12. Which of the following reaction will take place? a. Mg + LiOH → No Reaction b. 6Na + Al2(SO3)3 → Yes, 3Na2SO3 + 2Al c. Hg + CuS → No Reaction d. None of the above 13. What happens to Na2SO4 when mixed into water? It dissolves 14. Which of the following will not break up upon being mixed into water? c. Mg(NO3)2 d. FeCl3 a. NaCl b. NO2 15. Which of the following will break up upon being mixed in water? b. AgCl c. Ba(OH)2 d. MgO a. CaCO3 16. Write the net ionic equation for the following pair of reactants? AgNO3 + NaOH→AgOH(s) + NaNO3 Ag+ + OH- → AgOH(s) 17. `What are the spectator ions in the previous reaction? Na+ and NO3 18. Write the net ionic equation for the following pair of reactants? Fe(NO3)2 (aq)+ MgS (aq)→ FeS(s) + Mg(NO3)2 Fe+2 + S-2 → FeS 19. Suppose we were doing an experiment in which we were trying to predict precipitates formed in double replacement reactions. We find that many of these reactions yield precipitates yet one of them, between NaCl and Mg(NO3)2, does not. What is the correct explanation for this? both products are soluble in water 20. The following data table was generated by a student by mixing two ionic compounds together and then writing down the results. The student’s data is listed below: Na2SO4 MgCl2 Ba(NO3)2 White precipitate No precipitate NaOH No precipitate White precipitate Based on the student’s data above, which of the following substances is one of the precipitates formed in the lab above? a. NaCl b. Mg(NO3)2 c. Ba(OH)2 d. BaSO4 21. In redox reactions oxidation is always coupled with what? reduction 22. Define the terms oxidation and reduction. LEO the lion goes GER 23. What three substances can be added freely to a redox reaction occurring in an acidic solution in order to balance a half reaction? Water(H2O) H+ and e24. What is meant by “half reaction” in reference to a redox reaction? 25. In a redox reaction the number of electrons in the oxidation half reaction must equal the number in the reduction half 26. What is the oxidation number of “Cr” in MgCr2O7? +6 27. What is the oxidation number of “P” in PO43-? +5 28. Identify what is oxidized in the following reaction. +1 –2 +1+5-2 0 +2-2 +1-2 3H2S + 2HNO3 → 3S + 2NO + 4H2O reduced oxidized 3e- + 4H+ + NO3- → NO + 2H2O 29. Identify what is reduced in the reaction from the previous problem. Nitrogen 30. Identify the oxidizing agent in the following reaction. KMnO4 + HCl → MnCl2 + Cl2 + H2O + KCl Just Mn is OK 31. Balance the following 1/2 reaction. 5e- + 8H++ MnO41- → Mn2+ +4H2O -5+ +7=+2 +2 32. What half reaction is shown above? Reduction 33. Which of the following correctly balances the following 1/2 reaction? 2Cl1- → Cl2 +2e34. What half reaction is shown above? oxidation 35. What is the net ionic equation for the following Pb(ClO3)2 (aq)+ NaI (aq) → PbI2 (s) + NaClO3 Pb+2 + I- → PbI2 (s) MOLE: 1. Avagadro’s number tells us what? Particles in a mole. 2. Define empirical formula. Smallest whole number ratio 3. How many atoms are in a sample of an element whose mass in grams is numerically equal to its atomic mass? 6.02 X1023 4. What kind of substance is represented by a formula unit? Ionic compound 5. The molar mass of individual elements is generally expressed in which unit? g/mol 6. How many ions of Cu+2 are there in one formula unit of Cu3(PO3)2? 3 7. The mass of each element in a compound compared to the entire mass of the compound is called what? Percent composition 8. The percent composition of magnesium chloride, MgCl2, is? 24.3 + 2(35.5) = 95.3 24.3/95.3 = 25% 71/95.3 = 75% 9. What is the empirical formula for a compound whose molecular formula is C2Cl6? CCl3 10. What is the only possible molecular formula, from the choices below, for a compound whose empirical formula is CH? c. CH2 a. C2H d. need more info b. C2H2 11. If the empirical formula of a compound is found to be CH2, which of the following values are possible molecular molar masses? a. 21.04 b. 46.76 c. 12.01 d. 70.15 12. Which of the following correctly describes how to convert 250g of Ca(OH)2 into formula units? Convert 250g of Ca(OH)2 into moles by dividing by the molar mass and then divide that by 6.02x1023. a. Convert 250g of Ca(OH)2 into moles by dividing by the molar mass and then multiply that by 6.02x1023. b. Convert 250g of Ca(OH)2 into moles by dividing by the molar mass and then divide that by 6.02x1023. Once you have that number multiply by 3. c. Convert 250g of Ca(OH)2 into moles by dividing by the molar mass and then multiply that by 6.02x1023. Once you have that number multiply by 3. 13. Calculate the molar mass of LiOH. 24g/mol 14. How many F- ions are present in 2.50 moles of BaF2? 2.50 X 6.02X1023 = 1.5 X1024 X 2 = 3.0 X1024 15. If you have 2.87x1024 formula units of MgCl2, how many moles do you have? 4.77 mol 16. What is the volume of 16g of O2? 16/32 = .5 mol X 22.4 L = 11.2 L 17. If you have 348L of H2O vapor, how many moles do you have? 348/22.4 = 15.5 moles 18. If you have 26.4g of gold, how much of a mole do you have? 26.4g /197(molar mass) = .13 mol 19. What is the empirical formula of a compound that is 46.62% Na, 20.95% P, and 32.43% O? 46.62/23 = 2/.68 = 3 20.95/31 = .68/.68=1 32.43/16 = 2/.68 =3 Na3PO3 20. If a compound has an empirical of CH2O, and a molecular mass of 120g, what is the molecular formula? C4H8O4 21. What is the representative particle for P4O10? molecule 22. What is the representative particle for BaCl2? FU formula unit 23. How many grams of Mg are present in 150.0g of Mg3(PO4)2? 3(24.3) + 2(31) + 8(16) = 262.9 27.7 % Mg X 150 g = 41.6 grams 24. Define the term mole with respect to mass, volume, and representative particles.